Jenson Button said last night that his chances of becoming the first Briton to win the world championship in successive years will be slim thanks to the increasingly competitive nature of Formula One.

"It's getting more and more difficult," said Button on his return to Britain after taking the title in Brazil on Sunday. "It's a very competitive sport. I'm sure it was in the 70s and 80s but now, for me, every single driver on the grid deserves to be there. They are very talented; they're not paying their way into the sport."

Button was referring to the fact that 30 years ago, at least a quarter of the field would be made up of so-called rent-a-drivers whose wallets outweighed their talent. But, more than ever, the 2009 season has shown that sophisticated technology and the use of wind tunnels for aerodynamic refinement has meant there is little to choose between the cars themselves. In the 1960s and 1970s, when Jim Clark, Graham Hill and Jackie Stewart won championships, and even as recently as 1992 when Nigel Mansell claimed the title, some of the cars at the back of the grid were nothing more than make-weights.

"So, to have the competitiveness between the drivers, but also the teams – it's amazing how close it's been this season," said Button. "One second has covered the front to the back of the grid, whereas 10, 15 years ago that was first to third on the grid. It's a lot closer and it's made it a lot more difficult for everyone, as most sports have become a lot closer and a lot more competitive in recent years. It's going to be difficult but winning the championship is every driver's aim and that will be mine next season."

The closeness of the field has been a surprise in 2009, particularly as heavily revised technical regulations called for the most substantial changes to the cars since 1983. Button made the most of an advantage at the start of the season thanks to the Brawn team finding a loophole with the design of the double diffuser at the rear of the car. It took rivals such as Red Bull and McLaren time to catch up.

"That's true up to a point," said Button. "But, even without the double diffuser, Red Bull were very quick at early races such as Malaysia. It's been close all the way through. If you made a small mistake in qualifying – like I did in Valencia – then instead of dropping a couple of places on the grid, you could go from fourth to 14th. And that made a massive amount of work in the race."

The changes for 2010 will be less than in 2009, thus allowing the teams to hone their cars even more. The most significant difference will be the absence of refuelling, a radical change which should suit Button's smooth style as drivers are forced to look after their tyres while carrying a heavy load of fuel in the early laps.